Revive That Old Analog Cell Phone With SDR

With the latest and greatest 5G cellular networks just around the corner, it might be hard to believe that it wasn’t so long ago that cell phones relied on analog networks. They are no longer in use, but it may only take a visit to a swap meet or flea market to get your hands on some of this vintage hardware. Of course, these phones from a bygone era aren’t just impractical due to their monstrous size compared to modern gear, but also because analog cellular networks have long since gone the way of the floppy disk.

But thanks to the efforts of [Andreas Eversberg] those antique cell phones may be coming back to life, even if they’re just within the radius of your local hackerspace. Its software allows the user to create a working analog base station for several vintage telephone networks used in Europe and the United States, such as AMPS, TACS, NMT, Radiocom and C450. You can go the old-school route and do it with sound cards and physical radios, or you can fully embrace the 21st century and do it all via software-defined radio (SDR); in both cases, calls to the base station and even between multiple mobile devices are possible with relatively inexpensive hardware.

[Andreas] has put together some outstanding documentation for this project, which begins with a walkthrough of how you can set up your DIY cell tower with traditional radios. He explains that ham radios are a viable option for most of the frequencies used and that he has had early success modifying used taxi radios. He even mentions that popular BaoFeng handheld radios can be used as a last resort, although not all protocols will work due to distortion in the radio.

If you want to take the easy way out, [Andreas] also explains how to replace radios with an SDR unit. This greatly simplifies installation and turns an entire bench full of radios and cables into something you can carry in your backpack if you’re so inclined. Its software has specific options for using LimeSDR and LimeSDR-Mini, but you should be able to use other devices with a little experimentation.

We before that reviewed the LimeSDR-Mini hardwaree, as well as covered its use in setting up DIY GSM networks.

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